1. Field of the Invention
The present invention relates to a circuit device and a portable device. In particular, the present invention relates to a circuit device and a portable device, each of which has regularly arranged external electrodes or openings.
2. Description of the Related Art
Heretofore, a circuit device incorporated in an electronic device has been used for cell phones, portable computers, etc. and thus designed to reduce its size, thickness, and weight. In recent years, a device called “CSP (chip-sized package)” of a wafer scale equivalent to a chip size has been developed.
FIG. 10 shows a CSP 66 of a size slightly larger than a chip size, which has a substrate 65 as a support substrate. In the illustrated example of FIG. 10, a transistor chip T is mounted to the substrate 65.
A first electrode 67, a second electrode 68, and a die pad 69 are formed on the front surface of the substrate 65, and a first back electrode 70A and a second back electrode 70B are formed on the rear surface thereof. The first electrode 67 and the back electrode 70A are connected through a through hole TH. In addition, the second electrode 68 and the second back electrode 70B are electrically connected through the through hole TH.
The transistor chip T is attached to the die pad 69 to connect an emitter electrode of a transistor with the first electrode 67 via a metal thin line 72. Further, abase electrode of the transistor is connected with the second electrode 68 via the metal thin line 72. Furthermore, a resin layer 73 is formed on the substrate 65 to cover the transistor chip T.
In the CSP or other such circuit devices, external electrodes 76 are formed with soldering or the like on the rear surface of the device for receiving/transmitting electrical signals from/to any external device. The CSP 66 is attached to a conductive path 78 formed on the surface of a mounting board 77 through the external electrodes 76. This technology is described for instance in Japanese Patent Application Publication No. Hei 11-274361.
However, in the aforementioned CSP 66, the external electrodes 76 are formed in predetermined positions on a plane in accordance with the specifications of a user. That is, the external electrodes 76 are not arranged regularly on the plane. Therefore, when mounted to the mounting board 77, the CSP 66 should be placed under constraints of the mounting direction. This leads to a higher cost for mounting the CSP 66. In particular, portable devices such as cell phones have a limitation of installation space. Thus, the constraints of the mounting direction of circuit elements hinder the size reduction of the portable devices.